Well this thread has turned into a battery discussion, but I do find the comments "illuminating." I connected offline with BPL member Ben who travels extensively internationally and uses a Steripen Adventurer. He says one set of CR123 lithium batteries can last him 1.5 to 2 months of daily or near daily use.

While Brendan raises a good point about the superior runtime of the AA model Zebralights (the same applies to the AA Steripens that last twice as long), I do wonder if the smaller form factor and ability to carry a spare battery favor the the CR123 models.

I'll say as a flashaholic that the cr123 cell has a significant following in the light world mostly because in the size/power equation it is the best cell. The brightest and lightest lights almost always use them. Some of that stems from surefire who dominantly use the cr123. And high end lights like mcgizmo as well.

None of which necessarily translates to lightweight backpacking other than cr123 lights will generally be smaller lighter and brighter than single cell aa lights (14500 compatible lights excepted). The cost is usually runtime as the larger aa has a higher power density. Of course an 18650 has even more power reserves and output... but much larger.

Ultimately you need to pick what you are comfortable with based on your needs. I'd likely not through hike the at with a cr123 light but am comfortable in week long settings - my modded Novatac will run for more than 30 days at the lowest level which is fine for around camp activities if not hiking.